连续变焦镜头凸轮曲线压力升角优化研究

Pressure Angle Optimization for Cam Curve of Continuous Zoom Lens

连续变焦镜头凸轮曲线压力升角优化设计是镜头性能的重要影响因素。结合镜头中凸轮驱动结构形式及力学理论,分析了凸轮曲线的压力升角对系统传动力矩的影响;结合机械加工误差以及压力升角模型,提出凸轮曲线优化约束条件及优化原则;同时借助Gauss函数的平滑特性,实现凸轮曲线沿垂直于光轴方向非均匀展宽的优化方法,抑制凸轮曲线的最大升角。结合Gauss函数寻优处理对某光学设计获得的变焦凸轮曲线进行优化,在约束条件限制下保证曲线平滑性,凸轮曲线压力升角的范围由0°~39.01°优化到15°~31.16°,最大升角降低了20.12%。结果表明,该方法能够有效地应用于凸轮变焦系统设计以提高系统的性能。

For continuous zoom lens,the optimal design of pressure angle of cam curve is an important factor influencing the function of the lens.Based on the cam driving structure and mechanics theory,an analysis is made to the influence of the cam curve’s pressure angle on the transmission torque.With consideration of the machining error and pressure angle model,the constraint conditions and optimizing principle are proposed.By using the smooth characteristic of Gauss function,the optimization method of non-uniform widening of the cam curve is realized along vertical direction of the optical axis,and the maximum pressure angle of the cam curve is restrained.The method has been applied for optimization of a cam curve of a zoom lens obtained by optical design,for which the range of pressure angle is optimized from 0°~39.01° to 15°~31.16° under constraints,and the maximum pressure angle is reduced by 20.12%.These results indicate that the method can be effectively applied to the design of cam zoom system for improving the performance of the system.